Nutrients Flashcards
Which macromolecules can plants build using only water and CO2?
Carbohydrates and lipids
Why do plants need nutrients if they can build quite a lot out of just CO2 and water?
Anything in the plant that actually does something needs atoms other than just carbon, hydrogen, and oxygen
What elements make up chlorophyll?
Carbon, hydrogen, oxygen, nitrogen, magnesium
What is an essential element?
Any atom that is required for a plant to complete its life cycle
Is an element that is only required for reproduction still an essential element?
Yes
How do we test if one particular nutrient is essential for a plant?
Hydroponics
Why is growing plants in water problematic? How do we get around that with hydroponics?
Anything water saturated is anaerobic, and the roots need oxygen. Hydroponics pumps air into the water to supply the roots with oxygen
In a hydroponics experiment that tests if a particular nutrient is essential, what would the control be?
Plant grown in a complete nutrient solution
Does every single plant need the same nutrients in the same amounts?
No, lots of variation between plants
How are the vast majority of nutrients transported in the plant?
Dissolved in water and drawn up with it in the xylem
How do plants in humid environments like cloud forests keep drawing up nutrients?
They actively transport water out of their leaves to keep the tension in the xylem to keep bringing up nutrients
Which 9 elements are always required in large quantities?
- Carbon
- Oxygen
- Hydrogen
- Nitrogen
- Phosphorus
- Calcium
- Potassium
- Sulfur
- Magnesium
What are macronutrients? How much of the plant do they make up?
Nutrients needed in large amounts. They make up 96% of the plant biomass, with 95% of that being just C, H, and O
What are micronutrients?
Nutrients only required in small amounts
Why are micronutrients required in small amounts? What do they do in plants?
They are often toxic in high amounts. Often are involved in enzyme function
What does an iron deficiency look like in a plant?
Chlorosis and yellowing from the inside out
What does a magnesium deficiency look like in a plant?
Mottled chlorosis and leaf deformation, necrosis on the tips of the leaves
What does a nitrogen deficiency look like in a plant?
Leaves turn completely yellow and the lower leaves get sacrificed first
What does a sulfur deficiency look like in a plant?
Leaves are entirely yellow or mottled and the upper leaves get sacrificed first
What does a phosphorous deficiency look like in a plant?
Leaves are deformed towards the top of the plant, but all the leaves stay green because chlorophyll is unaffected
What does a potassium deficiency look like in a plant?
Necrosis around the edges
What does a calcium deficiency look like in a plant?
Odd necrosis patterns
Which other nutrient deficiency does a nitrogen deficiency look a lot alike to? How do you tell them apart?
Looks a lot like a sulfur deficiency. Nitrogen deficient plants lose their lower leaves first, and sulfur deficient plants lose their upper leaves first
What determines nutrient availability in the soil? Why?
If there are charged particles in the soil. They will attract ions of the opposite charge and immobilize them
What determines how much nutrients are available to plants?
pH and charged particles in the soil
Is nutrient uptake by plants active or passive transport?
Mostly active transport for better control, but some are passive transport
What is leaf senescence?
The final stage of leaf development which involves the reuptake of nutrients in the leaves by the plant
Why is leaf senescence critical to plant’s fitness?
Nutrients are hard to come by, and the plant would lose a ton of nutrients if the leaves fell off before the nutrients were reabsorbed. Also molecules like chlorophyll are expensive to make
What is nutrient salvage?
Hydrolysis of macromolecules followed by remobilization towards the roots
Which hormones regulate the onset of leaf senescence?
Ethylene and ABA
What signals the beginning of leaf senescence?
External stimuli like light and temperature, which determines the balance of hormones
What tissue in the leaves is the last to be broken down?
The vascular tissue, especially the phloem. It needs to be intact to transport the nutrients into the roots
What is the final stage of leaf senescence? What triggers it?
Leaf abscission. Triggered by ethylene and ABA
